Very original thought...
I think in the near future (10-50 years) ASICs at 10nm-1nm will be energy efficient enough.
Also, I do not think that Bitcoin requires infinitely increasing number of nodes to function, only needs large number of nodes with sufficient hashing power to prevent someone from mounting a 51% attack.
The currently established model, having few large pools containing majority of the hashing power, I think will be an adequate match to the network's growth challenge to quite a degree.
I don't see how quantum mechanical effects could be suppressed to make 1nm technology viable. Expect it to stop on a few nanometers.
Bitcoin will need to keep growing its computational power because the bigger it gets the more value it has to succeed in a 51% attack. So the pressure to break the network will increase with its market cap.
It is effectively an arms race.
So while it is true that we only need enough power to prevent an attack, the attack severity will also increase.
But i was interested in the
energetic picture.
Not sure how the model of pool operators helps clearing that up.